Broadcast Storms from Network Loops | Generated by AI
Question: 1. In a switched network, what causes a broadcast storm?
A) Too many unicast frames
B) Network loops without STP
C) Misconfigured VLANs
D) High bandwidth usage
- [The user indicates the answer is B]
Answer:
Question 1 Explanation
In a switched Ethernet network, a broadcast storm occurs when broadcast or multicast frames flood the network uncontrollably, consuming excessive bandwidth and potentially bringing the network down.
The primary cause is network loops without Spanning Tree Protocol (STP) (or a similar loop-prevention mechanism).
- When a physical loop exists in the topology (e.g., two switches connected by multiple links without proper configuration), a broadcast frame sent by a device enters the loop.
- Each switch forwards the frame out all ports (except the incoming one), so the frame circulates indefinitely.
- Each circulation generates additional copies of the broadcast frame, leading to exponential growth in traffic — this is the broadcast storm.
Why the other options are incorrect:
- A) Too many unicast frames: Unicast frames are sent to a specific MAC address and do not flood all ports unless the destination is unknown. Excessive unicasts may cause congestion but not a self-perpetuating storm like broadcasts in a loop.
- C) Misconfigured VLANs: VLAN misconfigurations can lead to traffic leaks, security issues, or suboptimal paths, but they do not inherently create the infinite frame multiplication seen in broadcast storms.
- D) High bandwidth usage: This is a symptom or result of a broadcast storm, not the cause.
STP prevents this by detecting loops and logically blocking redundant paths, stopping infinite frame circulation.
Question 2 Feedback
Your selected answer B) Network loops without STP is correct.
This is a classic networking concept tested in certifications like CCNA.